Thanks for posting the pictures Gary! There are some interesting scenes there....

The red challenger is painted just like I have seen in the advertisements with the black front hubcaps and the black locking ring for the rear wheels.
I will post a picture of the US edition of the 1938 Challenger / Pacemaker advertisement. (The canadian version has two Pacemakers in this same position.)

Also on the green Challenger. This tractor is a very interesting one, more than likely a pre-production challenger or one of the first 5. The differences of the very first ones are different drawbar, if you can see the radiator it should have the "Massey Harris" cast separate from the radiator top and bolted on like the 12-20's. The radiator top also has the oval cap like the 12-20 instead of the round challenger cap. This Challenger also has a 12-20 head on it yet! The more I look the more odd things I see. There is also a parking brake like the 12-20's on it.
And I almost forgot the different hood decals that do not say "Challenger"